As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users are information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes, thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems, e.g., computer, personal computer workstation, portable computer, computer server, print server, network router, network hub, network switch, storage area network disk array, RAID disk system and telecommunications switch.
An information handling system may be powered from a power supply that receives and converts alternating current (AC) power to direct current (DC) power at utilization voltages required by the electronic modules comprising the information handling system. The power supply tightly regulates these utilization voltages and incorporates over current protection for each of the voltages. To further provide increased reliability of the power supply, a plurality of power units (PUs) may be provided and coupled in parallel so that the loss or malfunction of one or more of the PUs will not totally disable operation of the information handling system. For critical applications the power supply may be powered from separate alternating current (AC) power sources, e.g., from independent utility power grids, so that the loss of primary power from one power source will not totally disable operation of the information handling system.
A power supply would require N+1 PUs for DC redundancy. For AC redundancy the power supply would require N+N PUs with N/2 of the PUs being connected to different independent AC power sources, e.g., each AC independent power source being supplied from a different power grid connection. Requiring N+N PUs for full AC redundancy is overkill compared to only needing N+1 PUs for DC redundancy.
Another issue is that a power supply in larger information handling systems, e.g., large server systems, blade server systems, etc., may reach or exceed the standard IEC connector limit which is about 2500 watts. Power requirements for a large information handling system may exceed 5000 watts. Therefore, a fully AC redundant power supply having N+N PUs will require a plurality of standard AC line cords connected to the N+N PUs. This is both expensive and wasteful because half of the power available is never used except in a fault condition. The N+N PU AC redundant system also is oversized in DC power capacity since only N+1 PUs are needed for DC redundancy.